This is topic SCREEN SIZE ENQUIRY in forum 16mm Forum at 8mm Forum.
To visit this topic, use this URL:
https://8mmforum.film-tech.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=5;t=000639
Posted by Den Brown (Member # 819) on May 08, 2011, 01:04 PM:
If an Elf NT projector is fitted with a long throw lens (F1.6 - 63mm), what size would the projected image be if the projector is 41 metres (134ft) from the screen?
Also, would this projector/lens combination give a bright enough picture from this distance?
.
Posted by Michael O'Regan (Member # 938) on May 08, 2011, 01:15 PM:
H - 4.43M
W - 5.93M
Posted by Wayne Tuell (Member # 1689) on May 08, 2011, 02:26 PM:
Den, does your projector use a XENON bulb or ELC bulb? That is asking a lot for an ELC using a f1.6 lens. Is there any ambient light that may interfere? Try a trial projection run before you invite a crowd to see if the image would be adequate.
I was told my old 1000 watt XENON was not enough for that distance...I don't know how true it is/was being I couldn't get private use of the drive-in anyhow to test it.
http://paulivester.com/films/projector/throw.htm
Posted by Michael O'Regan (Member # 938) on May 08, 2011, 02:38 PM:
Ah, thanks Wayne. I couldn't locate that chart. I tried to link to the chart on the efilm center page but I wasn't allowed for some reason.
Posted by Den Brown (Member # 819) on May 08, 2011, 02:41 PM:
Wayne,
Thanks for the tips. No, it's an ELC 250 watt lamp. The farthest I have projected from before with it was about 20 metres, so doubling that is a bit of a step.
May have to try to get closer to the screen somehow.
As for ambient light, we'll be outside with a 13% moon.
Michael, cheers for the dimensions.
Posted by Jeff Taylor (Member # 442) on May 11, 2011, 04:00 PM:
FWIW, I've seen some discussions about lumen output/throw distance/screen sizes on Film-Tech, which is largely populated by actual techs and projectionists (in addition to being the parent of this forum). Whether true or not, I have repeatedly read that throw distance is far less important than screen size in calculating required light output to achieve satisfactory results, which are defined generally as 16 footlamberts. By this theory, while the efficiency of the lens and the gain of the screen bear on the question, the total throw distance is less of a factor. Pay your money and take your choices!
Visit www.film-tech.com for free equipment manual downloads. Copyright 2003-2019 Film-Tech Cinema Systems LLC
UBB.classicTM
6.3.1.2